[HOT] HOT carto, Re: Buildings and residential areas: Buldings as nodes (Q1)
john whelan
jwhelan0112 at gmail.com
Thu May 25 16:49:24 UTC 2017
> Buildings as nodes is not a recognized way of mapping them that has
broad support. Almost without exception the only people doing this are
newbie HOT mappers who don't know the correct procedure. So this is a
mistake that should be fixed, just like non-square buildings or
unconnected roads.
I do a lot of validation and clean up on HOT projects and in the areas they
map. I usually check the number of edits a mapper has done and in my
experience HOT mappers may map a building three times, they may not square
buildings, the buildings might be three times the size they should be, they
map them in odd shapes. I see villages tagged building=residential but its
very rare that I see buildings as nodes from HOT mappers. Generally they
look at the training guides which describe mapping buildings as ways.
The mappers I have seen using nodes for buildings, typically tagging nodes
building=hut, are generally experienced mappers who have used nodes for
street numbers in the past often from Europe. When I come across them I
generally mention that the HOT convention is to map the outline.
The concerns I do have about mapping buildings as ways are more on the data
quality side. I'm currently looking at Malawi and I'm seeing a number of
sites where buildings have been mapped multiple times and I've added tags
to a few hundred that have been left area=yes. Some of these are more than
a month or two old.
Personally I'd like to see more use of the JOSM building_tool plugin
because at the moment there are many areas where you cannot depend on all
the buildings having been mapped, mapped just the once or that the area of
the building is anywhere near correct.
Cheerio John
On 25 May 2017 at 11:08, Andrew Buck <andrew.r.buck at gmail.com> wrote:
> The real solution is to "upgrade" these nodes into properly mapped
> buildings with a way. We really should be discouraging people mapping
> as nodes like this as it is largely a waste of time since someone has to
> map it as a way later on anyway and when they do they either need to
> delete the existing nodes or merge them into the buildings to preserve
> history (but also taking much longer).
>
> Adding renderings to maps only encourages people to take the easy way
> out in the short term and create more bad data. We should not encourage
> this and should be actively trying to fix the nodes already in the
> database. I have done this on a few occasions and have probably knocked
> out a few thousand of them, but unless we get serious about cleaning
> them up we will end up with more and more of them.
>
> Buildings as nodes is not a recognized way of mapping them that has
> broad support. Almost without exception the only people doing this are
> newbie HOT mappers who don't know the correct procedure. So this is a
> mistake that should be fixed, just like non-square buildings or
> unconnected roads.
>
> -AndrewBuck
>
>
> On 05/25/2017 04:09 AM, Bjoern Hassler wrote:
> > Hi all,
> >
> > just to follow up on the buildings discussion - it seems that it's not
> > likely that node-buildings will be rendered in the standard cartography,
> > see https://github.com/gravitystorm/openstreetmap-carto/issues/806.
> >
> > However, I think there is a case for rendering node-buildings in the HOT
> > cartography? I'll file a suggestion here: https://github.com/
> > hotosm/HDM-CartoCSS.
> >
> > Bjoern
> >
> > On 23 May 2017 at 04:54, Rob Savoye <rob at senecass.com> wrote:
> >
> >> On 05/22/2017 01:44 PM, john whelan wrote:
> >>
> >>> consider and it is a major part of engineering. No matter what
> >> compression
> >>> system is used four nodes will always take up four times the space as
> one
> >>> node. Maybe not with .7z compression looking for strings in the long
> lat
> >>> but its a good rule of thumb. Again OSM is now running the largest
> >>> database known in whatever it is running in, I forget the name. It's
> >>
> >> OSM uses PostgreSQL with the postgis and hstore extensions. I run it
> >> locally to save on bandwidth latency, plus it works offline too cause
> >> connectivity is poor around here. Mobile bandwidth is getting better all
> >> the time all over the planet though. Adding data to OSM is better to be
> >> done the way most others do it than worrying about bandwidth.
> >>
> >> Looking into a few OSM files, I see <node> used as a building that
> >> hasn't been mapped as a polygon, ie.. just a waypoint. That's useful
> >> enough for most people trying to find someplace. For a building that
> >> actually has it's dimensions mapped, then it's a <way>, with references
> >> to each <node>. It depends what type of info you want from your map.
> >> When generating a display map, a <node> won't appear as a building,
> >> it'll just be a cute icon. If you want to see a whole building shape, it
> >> needs to be a <way>. Some buildings have both.
> >>
> >> - rob -
> >>
> >> _______________________________________________
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> >>
> >>
> >
> >
> >
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>
>
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